1. Field of the Invention
The present invention relates to a signal transmission film for a compact size liquid crystal display (LCD), and more particularly to a signal transmission film capable of receiving both of gate signal and data signal which are processed in a single integrated printed circuit board and transmitting the processed signals to an LCD panel and another signal transmission film. Further, the invention relates to a liquid crystal display panel to which the signal transmission film is applied.
2. Description of the Related Art
Generally, an LCD is a mostly used type of flat panel display. Especially, the small size, lighter weight and lower power consumption render the LCD to replace the traditional cathode ray tube (CRT). The LCD is currently used as a monitor for a lap-top computer and even for a desktop computer, gaining its popularity.
As shown in FIG. 1, an LCD includes an LCD panel 101 and a light supply unit. The LCD panel 101 includes a TFT substrate 10, a color filter substrate 20, multiple gate tape carrier packages(TCPs) 30 connected to gate lines (not shown) of the TFT substrate 10, multiple data TCPs 40 connected to data lines (not shown) of the TFT substrate 10, a gate PCB 50 connected to the multiple gate TCPs 30, a data PCB 60 connected with the multiple data TCPs 40. The light supply unit includes multiple optical sheets such as a light guiding plate 90, a light diffusing plate (not shown), etc., a lamp assembly 80, and a receiving case called as “mold frame”. The light guiding plate 90 has a decreasing thickness as it travels from the lamp unit 80 to the data PCB 60.
A power supply unit and a controller that processes gate signals and data signals coming from an external device are mounted on the data PCB 60. A gate voltage supply part (not shown) is formed on the gate PCB 50 and supplies a gate driving voltage to gate lines by a control signal from the controller on the data PCB 60.
To supply the control signal and the gate driving voltage into the gate PCB 50 from the data PCB 60, connectors 55 and 65 are respectively installed in the gate PCB 50 and data PCB 60 and are connected to each other through a connecting member 70, “flexible printed circuit (FPC)”.
Semiconductor fabrication technologies have developed in the areas of thin film formation, and packaging. This allows semiconductor devices to be mounted on the gate PCB 50 and to function as gate power supply source on the data PCB 60.
Under such a configuration, the gate PCB 50 only transfers to the gate TCP 30 gate driving signals processed in the data PCB 60.
The conventional LCD has following problems.
First, in order to apply gate driving signals processed in data PCB 60 to gate PCB 50, gate PCB 50 and data PCB 60 need connectors 55 and 65.
The connectors 55 and 56 are generally installed on the front surface or on the rear surface of the PCBs 50 and 60. This increases the thickness of the LCD and makes it difficult to achieve a compact size LCD.
And the flexible printed circuit (FPC) 70 that connects the connector 55 and the connector 65 complicates the assembly process and increases the fabrication costs.
Finally, a bent type PCB that is mostly used currently bends a gate PCB 50 and data PCB 60 and they are fixed at the rear surface of the reflecting plate of a back light assembly. In such a configuration, the data PCB 60 is put in a space between a relatively thin side edge 92 of the non-symmetric light guiding plate 90 and the mold frame. Thus the data PCB 69 does not increase the thickness of the LCD much. On the other hand, the gate PCB 50 is put in a space between a thickness varying side of the light guiding plate 90, and the mold frame. Specifically, one side of the gate PCB 50 is attached to a thick portion of the rear surface of the light guiding plate 90, making a thick LCD depending on the thickness of the light guiding plate 90.